I know I should be using a Yeast Starter so that I can make sure I have enough, healthy yeast, but I've never managed to go around to it.
How would I start a yeast starter? How long before brewday should I start?
One thing that I think makes using starters a lot easier is preparing a bunch of starter wort at one time, keeping quarts in canning jars and then when you are ready to make your starter, all it really takes is a clean vessel, your yeast and a jar of the wort. Making it so much easier will really encourage its use and as you point out, it is a big help to have a starter.
So get a load of quart sized canning jars, make a 3 gallon batch of wort with extract, fill the jars, put them in a water bath in your brewkettle, bring to a boil to seal, let cool and stash in a convenient location. Next time you are brewing, pop one out a couple days before to make your starter.